Recently, technologies that improve the winding density of a stator winding are variously proposed by so-called distributing winding the stator winding in a stator core in order to miniaturize, make highly effective and reduce noise in an electric motor installed in a vehicle etc.
For example, density growth is achieved by continuously forming a flat lead wire as disclosed in JP 2001-211621.
However, in the forming like the above-mentioned JP 2001-211621, since the winding of the lead wire at a coil end of the stator winding (a part that projects from an end portion in an axial direction in the stator core) is needed to be bent a plurality of times, damage to an insulation film that covers a surface of the lead wire increases.
Moreover, when a fat lead wire is adopted to reinforce an output density grows, the damage to the insulation film becomes further more because a load necessary to bend the lead wire becomes large, too.
Therefore, it becomes necessary to thicken a thickness of the Insulation film, or paint the film in many layers by using different materials, and thus results in a high cost.